Bwin.party was boosted higher on Monday, as a US crackdown on online poker firms is expected to bolster demand for its more Europe-focused peers. The Federal Bureau of Investigation (FBI) has forced a shutdown on Friday of three popular poker websites, Full Tilt Poker, Pokerstars and Absolute Poker, claiming that the sites "concocted an elaborate criminal fraud" and were involved in "massive money laundering and bank fraud". Shares in the UK-listed company rose by 34% on Monday.Meanwhile, Heritage Oil is the worst performing stock, after being slapped with a $313.45m lawsuit byTullow Oilrelated to the sale of Heritage's 50% interest in Blocks 1 and 3A in Uganda. The bone of contention is Heritage's refusal to reimburse Tullow in relation to a recent payment made by Tullow of $313,447,500 to the Uganda Revenue Agency (URA). Heritage believes that the claim has no basis and will vigorously and robustly defend it.Not far behind is Irish mining firm Kenmare Resources, even though it said that its Moma titanium minerals mine is producing in line with expectations, while plans to increase total production by 50% in 2012 are on schedule. Engineering software firm Aveva is also lower despite saying that it expects full year results to be in line with expectations after a good performance in Asia Pacific Oil and Gas and Power sectors. Comet store owner Kesa Electricals is unwanted after RBS cuts its target price by 20p to reflect weaker UK trading a higher tax rate. A 'buy' was retained. FTSE 250 - RisersBwin.party Digital Entertainment (BPTY) 175.00p +33.59%Micro Focus International Plc (MCRO) 310.00p +6.24%Yule Catto & Co (YULC) 202.30p +5.25%Home Retail Group (HOME) 219.00p +3.06%Jupiter Fund Management (JUP) 295.10p +2.22%Exillon Energy (EXI) 435.00p +2.04%Domino Printing Sciences (DNO) 607.50p +1.93%Ladbrokes (LAD) 146.20p +1.32%Enterprise Inns (ETI) 90.80p +1.23%Cranswick (CWK) 757.00p +1.07%FTSE 250 - FallersHeritage Oil (HOIL) 255.70p -5.30%Kenmare Resources (KMR) 47.25p -4.70%Aveva Group (AVV) 1,542.00p -3.20%Morgan Crucible Co (MGCR) 281.60p -3.16%Domino's Pizza UK & IRL (DOM) 387.80p -3.12%Hochschild Mining (HOC) 588.00p -3.05%Carpetright (CPR) 662.00p -3.00%Afren (AFR) 153.50p -2.97%St James's Place (STJ) 335.40p -2.92%Paragon Group Of Companies (PAG) 166.60p -2.80%